The wording "compositions applied in the mouth" used in the present disclosure refers to compositions used in the mouth, for instance, for dentifrices in the pastes, powders and gels, mouthwashes and gargles, oral refrigerants in the chewing gum, candy, liquid and pellet forms, caries preventive agents in the paste and liquid forms, tooth make-up agents and the like.
A dentifrice is a substance or preparation used with a toothbrush to aid mechanical cleaning of the accessible surfaces of the teeth. A typical formulation for a dentifrice paste contains abrasives, flavoring mixture, humectants, thickening agents, foaming agents and water. So far, teeth reinforcing agents such as fluorides, enzyme inhibitor such as vitamin K and sodium N-lauroylsarcosine, germicidal agents such as hexylresorcin or nicotinnic acid amide have been used with the dentifrice compositions for the purpose of preventing tooth decay. However, such materials have both merits and demerits, and no utterly satisfactory materials are still found. For instance, it is widely accepted that the fluorides serve to reinforce teeth, but limitations are imposed upon the amount thereof in view of toxicity in vivo. Sodium N-lauroylsarconsine produces a less stimulating action, is of low toxicity and has a strong fermentation preventive action, but is somewhat of a bitter taste and does not have sufficient antibacterial properties. Recent studies have revealed that the traditional "tooth black" used previously in Japan serves to prevent dental caries. The tooth black comprises a powder containing tannic acid as the main component and a solution containing ferrous acetate as the main component. The powder and the liquid are mixed and applied on the teeth. Among these, tannic acid is found to serve to flocculate and astringe tooth protein, whereby tooth is reinforced, and to possess antibacterial and antienzymetic properties useful for the prevention of caries. However, tannic acid easily undergoes coloration, especially blackens, so that it is aesthetically unpreferred. For that reason, extreme restriction is placed upon its use.